Magnetic alloy



Patented Aug.. 12, 1930 UNITED STATES PATENT OFFICE BRUNO FETKENHEUER,OF IBEBLIN-BEINICKENZDORF, AND HANS .NEUMANN, OF BERLIN, GERMANY,ASSIGNORS TO SIEMENS & HALSKE AKTIENGESELLSGHAFT, OF SIEMENSSTADT, NEARBERLIN, A CORPORATION OF GERMANY maonnrrc Armor No Drawing. Applicationfiled May 7, 1928, Serial No. 275,955, and in Germany May 20, 1927.

Our invention relates to improvements in magnetic alloys, and its objectis to produce a material the properties of which make it especiallyuseful for the cores of transformers, Pupin or loading coils and thelike, as well as a wrapping for conductors in order to increase theirinductivity.

Magnetic alloys are already known which contain nickel and iron and showa high magnetic permeability at low magnetizing forces. It has beenascertained that the favorable magnetic properties of these alloysdepend to a large extent upon the purity of the constituents employed.

It is, furthermore, generally necessary to produce these alloys in avacuum furnace.

We have ascertained that by means of tech nically pure materials analloy of good magnetic properties may be manufactured, by addingaccording to our invention about 5 to 20% of silicon to the alloy. Analloy which contains about 78% of nickel, 17% of iron and 5% of siliconhas proved particularly useful. In all cases the nickel may entirely orpartly be replaced by cobalt.

Alloys of this kind are very brittle and may therefore be easilypulverized. They have further a very high initial permeability and greatmagnetic stability as compared with other similar alloys known in theart. In particular in conductors equipped with coils having magnet coresof such alloys, the conditions are not noticeably varied by accidentalmagnetizations.

The most favorable magnetic properties of the alloys according to ourinvention develop after a suitable heat treatment, as in the case of theknown alloys. For developing a high permeability our allo sarepreferably annealed for a considera 1e time, say one hour at about900 C. and then allowed to cool down slowly say about 15 to 20 minutes,to aboutv 625 The alloyis maintained at this temperature for 15-to 30minutes, and is then cooled suddenly down to the room temperature,preferably in contact with air.

. Various modifications and changesmay be made without departing fromthe spirit and the scope 'of the invention, and we desired, therefore,that only such limitations shall be placed thereon as are imposed by theprior art.

We clalm as our invention:

1. A magnetic alloy of high permeability at low magnetizing forces,containing 5 to 20% of silicon, 15 to 28% of iron and a balance ofanother element of the ferrous group.

2. A magnetic alloy of high permeability tures.

BRUNO FETKENHEUER. HANS NEUMANN.

